Terminal wiring method and apparatus



Aug. 21, 1951 K, ANDRE-N 2,564,874

I TERMINAL WIRING METHOD AND APPARATUS Filed April 4, 1947 2Sheets-Sheet l E E 111.1111111111111) fil/1111111111111,umbrmmm.711111111111.

Aug. 21, 1951 K, ANDREN 2,564,874

TERMINAL WIRING METHOD AND APPARATUS Filed April 4, 1947 2 Sheets-Sheet2 www0/@MEMS Patented Aug. 21, 1951 TERMINAL WIRING METHOD ANDAPBARATUS.

Karl H. Andren, Milwaukee, Wis., assignor to Artos Engineering Company,Milwaukee, Wis., a corporation of Wisconsin Application April' 4, 1947.,Serial No.. 739,505

4 Claims. l,

The present invention relates in generalv to improvements in thev art ofattaching a succession of similar elements in predetermined. order to a,series of elongated members, and relates more specifically toan1improved method of and apparatus for electrically connectingsuccessive groups of terminals tosuccessive spaced porn tions of aplurality of insulatedwires or conductors.

It has heretofore been proposed as shown and described in my copendingapplication Serial No. 459,526, led December 19, 1942, now abandoned, toconstruct terminal banks for automatic telephone systems, bylongitudinally advancing a series ofinsulated Wires radially toward acommon axis', by positioning successi-Ve arcuate groups of radiallydisposed terminals adjacent to the wires of the advancing series nearsaid axis, by crimping correspondingr terminals of the successive groupsto the same wiresthrough the insulation of the latter so asA toV producea chain of elec- -trically interconnected terminal groups, and byfinally stacking the terminal groups into arcuate banks havingpredetermined terminals thereof connected by predetermined wires,without resorting to soldered attachments. While this crimping of theterminals through the insulation, did in fact greatly facilitateassembly of the terminal banks by eliminating the laborious and costlyprior method of soldering each terminal to aselected wire, it is'possible that the presence of the insulation at the attaching zonesmight occasionally prevent perfect electrical contact between theinsul'uation piercing prongs of a termina-l and the adjacent wireespecially when the attachments are being produced by machinery and inrapid succession. In` order to avoid this possibility of production ofimperfect electrical connections while still retaining the advantages ofthe crimping method of attachment and bank assembly, I have discoveredthat moreperfect and dependable unions may be secured with the samegeneral procedure and machinery as that revealed in my prior applicationand without interfering with speed of production, by positively removingthe wire insulation at the successive attaching zones before theterminals are crimped to the Wires at these zones.

it is therefore primary object of my present invention to provide animproved method of and apparatus for expediting attachment of successivesimilar elements such as groups of terminals, to a plurality ofelongated members such as insulated electric current conducting. wires,in a .manner whereby; perfect electrica-1l Connections (Cl. 22T-155.55)

2. are insured while the interconnected elements and members may stillbe readily assembled into final stacks such as efficient telephoneswitch banks.. e

Another object of this invention. is to provide ay methodY of.' directlyconnecting. arcuate groups of terminals to longitudinaly advancinginsulated wires, by removing the insulation from. successive local zonesor portions of the wires,yand by crimping selected terminals of. thesuccessive groups. to the baredareas. of predeterminedwires of. theadvancing l'ot.

A further object of.' the present inventionis to provide reliable and.automatically functioning apparatus for carrying on commercial,exploitation. of my improved method of terminal group and( conductingwire assembly, by effectively removing the insulation from the localportions of the. continuousY wiresand by subsequently firmly crimpingthe selected terminals to the bared zones..

Still another object of my invention is to provide an. improved. systemfor mechanically as sembling a, succession. of similar elements suchasfgroupsofmultiple switch terminals and a plurality of elongatedmembers such as continuous insulatedcopper wires, at high speed and in'a mest. accurate and dependable manner, so that perfect electricalcontact. between the terminals and the wires is always assuredwithoutresorting tofusionofmetals.such as soldering.

An. additional' obiect of .the invention is to provide a new mode ofmost effectively electrically connecting selected terminals ofsuccessive unitary cards. or groups, to bared local: zones. of insulatedlongitudinally advancing wires, while twisting adjacent. pairs of theprogressing wires about. each other on opposite sides of each zone ofattachment of a-terminal.

These and. other objects and advantages of the present invention. willbe apparent from the following. detailed description.

A clear conception of the several steps involved in my improvedI method,and of the construction and operation of typical apparatus for effectingautomatic commercial exploitationV thereof, may be had by referring tothe drawings accompanying and. forming a part of this specification inwhichY like reference characters designate the same or similar partsinthe various views.

Fig. 1 is a somewhat diagrammatic section through one of my improvedinsulated' wire clamping and insulation. removing or stripping units forholding, strippingy and transferring an adj-acentpair of wires.;

Fig. 2 is a similar section through the clamping and insulation removingunit, showing the same in action to strip the insulation from localareas or portions of the held wires;

Fig. 3 is a transverse section through the clamping and insulationremoving unit of Figs. 1 and 2 showing the complementary pair of wiresin position, the section having been taken along the line 3-3 of Fig. 1;

Fig. 4 is an end view of one of the wire spacers and stripping elements,removed from the clamping and insulation stripping unit;

Fig. 5 is a diagram of a. typical terminal and Iwire assembling machineshowing the movable terminal crimping die elevated, the wiretransporting slide moved away from the crimping Zone and lowered tobring the wire feeding and insulation stripping ngers thereof intoinsulation shearing action adjoining each other as in Fig. 1, while thewire twisting rotor is inactive;

Fig. 6 is another diagram of the machine, showing the wire feeding andinsulation stripping ngers of the transporting slide, moved apart as inFig. 2 to strip the insulation off of or away from adjacent local areasof the wires, and also showing the Iwire twisting rotor in action totwist the pair of wires about each other adjacent to the stripped zonewhile the wires are being transported longitudinally;

Fig. 7 is a similar diagram of the machine, showing the strippingfingers spread apart as in Fig. 6, and the wire transporting slide movedforwardly to position the bared portions of the wires close to the finalcrimping zone, while the wire twisting rotor is again inactive;

Fig. 8 is still another diagram of the machine, showing the strippedportions of the wires lowered adjacent to the terminals of an arcuategroup, and the movable crimping dies operating to effect attachment ofthe terminals to the bared wires, while the wire twisting rotor is stillinactive;

Fig. 9 is an additional diagram of the machine, showing the uppercrimping die and the wire feeding lingers and transporting slideelevated away from the crimping zone, but with the arcuate terminalgroup still held at the crimping zone and the wire twisting rotor activeto twist the adjacent pairs of wires;

Fig. 10 is a further similar diagram of the machine, showing thecrimping dies fully separated and the transporting slide and feedingngers being moved rearwardly, while the adjacent pairs of wires arestill being twisted about each other;

Fig. 11 is a final similar diagram of the machine, showing the crimpingdies fully separated and the feeding and stripping iingers about to bebrought together and lowered for coaction with a succeeding portion ofthe wires, while the wire twisting rotor is again inactive; and

Fig. 12 is an enlarged diagrammatic plan View of a fragment of thepartially completed chain of wires and terminal groups produced by themachine while carrying on my present improved method.

Although the invention has been shown and described herein as beingadvantageously applicable for effecting attachment of correspondingterminals of successive flat arcuate groups to the same insulated wiresof a series while the latter are being advanced longitudinally in ahorizontal direction, it is not my desire or intention to therebyunnecessarily restrict the utility of the improved method and apparatus.

In my prior application, Serial No. 469,526, led

December 19, 1942, I have revealed an improved method of electricallyconnecting or attaching the corresponding terminals of successivesimilar arcuate cards or groups, to the same longitudinally advancinginsulated wires of a series, and of twisting adjacent pairs of the wiresabout each other on opposite sides of the several points of attachment,by providing each individual terminal with integral metallic pointswhich were driven through the insulation and embedded within thestranded copper wires by cooperating dies, without removing theinsulation from the wires at the attaching areas. The presentimprovement contemplates the provision of a similar method, but theimproved method diiers from the prior one by virtue of the fact that Inow positively remove the insulation from each area of attachment of theterminals and wrap the metal of each terminal directly about the baredportion of the adjacent wire, thereby insuring more perfect electricalcontact without however resorting to soldering or the like. The improvedmethod may be carried on commercially with apparatus quite similar tothat shown and described in my said prior application, by merelyproviding additional mechanism for removing the insulation from theseveral wires at the proper localities, and the major portion of thisapparatus will therefore be only diagrammatically disclosed herein,while the modication necessary for the present improvement will be morespecifically shown and described.

Referring to the drawings, the apparatus shown is adapted toautomatically produce a continuous chain of wire and arcuate terminalgroup assemblages a partially completed fragment of which is shown inFig. 12, and as specifically illustrated, each arcuate card I4 consistsof a group of twenty sheet metal terminals I5 radiating from a commoncenter, to each of which an insulated wire I6 is electrically connectedby crimping the metal of the terminal I5 about a bared portion of theadjacent wire I6. The wires I6 may be either stranded or solid, and thecompleted chain may be severed into sections of suitable lengths eachcontaining a number of cards I4, and these cards may finally beassembled in stacks or banks for use in connection with automatictelephone systems, in a well known manner.

The apparatus for producing the improved chains of Fig. 12, comprises ingeneral a frame forming a crimping or card attaching Zone l1 havinglower and upper relatively movable dies I 8, I9 respectively cooperabletherein to simultaneously crimp all of the terminals I5 of eachsuccessive card I4 to the successive locally bared portions 2S of theseveral wires I6 presented to the zone I1; a revolvable card supplytable 2|; a card transfer and holding pad 22 cooperable therewith forproperly positioning the successive cards I4 within the zone I1; aplurality of horizontally reciprocable radially directed main slides 24each having thereon a set of wire gripping and insulation removingfingers 25, 26 adapted to cooperate with a pair of the insulated wiresI6 to transport these wires longitudinally toward the assembly Zone l1;a multiplicity of wire guiding and twisting rotors 21 each housed withinan independent casing 28 and each adapted to conduct a pair of theinsulated wires I6 toward the corresponding set of stripping andtransfer fingers 25, 26; a number of wire supply reels each having awire guide 29 cooperable therewith to conduct the individual wires I6 inpairs toward one of the rotors 21; a final conveyor 30 for transferrifngtheA continuous chain assembly away' from the uniting zone I1; andsuitable driving mech'- anismfor periodically actuating. the. various.machine' elements to automatically' exploitthe improvedV method.

The lower and. upper crimping' dies I8, I6 are formed' and operable tormly wrapv the. metal ofv the terminals i5 about the bared portions' 2Dof the adjacent wires I6, and-thereisl a cooperating set of these diesI8, is provided for each of the twenty terminals of the successive cardsor groups I4; The. card supply table 2I` isl intermittently revolvableto present the successive` cards I-f4A deposited: in spaced relation.upon the periphery thereof, to the positioning pad 227,. and` this padis movable. fore and. aft' uponv links 32A to: assist in the transfer ofthe new arcuate cards I'4 with their radiating terminals'. in' position'for distortion by the. dies I8. t9. within. the crimping zone I1, and toalso hold: the cards. while the dies are being withdrawn. Thereciprocable wire feeding slides 24 besides being' movable toward andaway from the assemblyA zone I1, are also movable vertically at certainintervals.. and the upper dies. I9 are movable through openings' or gapsbetween the spread fingers 25, 26. of the corresponding slides 2.4whenever a crimping operationk is: being effected.

The slides. 24 and the dies I8', I9` may all be mounted for movement inthe common sturdy frame, and each of the main slides 2l!` carries an`auxiliary. slide 34'. The front wire gripping and insulation removingfinger 25' of. each slide assembly'is carried directly by the auxiliaryslide 3:4-, whereas the rear. nger 26 is carried directly by the mainslide 24, and the two slides of each assembly are simultaneously movabletoward and away' from' the zone: i1: but they are also' relativelymovable'` to separate or spread the fingers 2.53, 26 asillustrated inFigs. 1 and 2?. Each finger 25, 26 isprovidedat its lower' end; with'.two laterally' spaced notches 35 each oflwhich ist bounded by a cuttingor knife edge. as shown. in Figs. 1, 2 and 3, and these knife edges areadapted to cut through the'. top and' sides of: the: insulation i 36 ofthe wires it presented thereto, while the fingers 25, 26 are in contactwith each. other as in l. When the fingers 25,. 26 are subd sequentlyspread apart by relativeI movement of the-s1ides 21%', 34 as.- in Fig.2, the knife edges of the` notches 35 remove or strip the' insulation 36to produce the bared wire portions 26,. but the notches. 35 continue tosnugly. embrace and to firmly hold the wires 61. after such strippinghas been eifected.

In. order `to properly position. the wires. I6. for entry thereof intothe notches 35 and to; prevent thel wires from dropping: or.'excessively sagging away'f'rom the descending. fingers 25, 26, a pairof: spreaders 31l such as shown in Fig. 4 are providedI at each of theslide assemblages.. Each cooperating set or pair of these spreaders 31is swingably suspended by means of pivotpins 38, from a verticallymovable supporting block 39, andthe spreaders 31 of each pair areconstantly urged toward each other by leaf springs 4l) secured to theintervening block 39 and coacting with thev adjacent spreaders 31. Eachspreader 31 is provided with an upwardly directed central point 42having projections'` 43' onthe opposite sides thereof, and thev top ofeach; of these prdjections 43 is provided witha cutting or knife edge 44which. iscooperablel with. the knife.Y edgesA of the adjacent orcorresponding: finger. 25, 26.r to and. strip the insulation. 36 fromthe bottoms ofsuccessiveportons 2070i the. wires IS-,asfclearly shown inFigs. 1. to 4Y inclusive in. order toinsure clean. cutting: of theinsulation entirely around. each wire. The points 42 of the spreaders31P are: always. spa-ced apart sufficiently to permit lower= ing ofthetransfer fingers 25, 26 therebetween, when these fingers are inengagement W-itheacha other; andas these fingers are moved away fromeach other: they move thespreaders apart. After` these. iingershave beenspreadV apart to: produce as bared wiresportion` 2D on a pair ofcomplementary^- wires I6, and the spreaders 31 have been lowered awayfrom thewires, the` leaf springs 40 become quickly effective to returnthe: released spreaders toward each other, to the position in;- dicatedin Fig. l'.

lThe wire guiding and: twisting rotorsA 21 which are. journalled forperiodic rotation within the fixed casings 28, are located' between theWire guides 29 and the wire spreaders 31, andi each of these rotors 21coacts with al complementary-pair` of the wires I6 to' guide this pairof wires for longitudinal advancement radially ofthe crimping; zone I1',and to also periodically twist the wires I6 about each other on theopposite sides of each successive pair of bared wire portions 201 Eachof these rotors 21 is provided with a pain of laterally separable wireguiding fingers which are normally held together by clamps 46, but;which' are adapted to separate and to twist thel wires I6 about eachother during variousdefinite periods of operation of the machine. Thema.- chine is also provided with other,y structuresl for insuring properguiding of the wires and for re'- leasing the cards I4 from the diesafter each crimping operation, and the mechanism for driving the variousmovable partszin properly timed relation, is shown and described indetail. in my copen'ding application above referredY to.

As previously indicated, the mechanism justdescribed is adapted toautomatically exploit: my new method, and in order to clearlyindicatethe manner in1 which. this is done, onev cycle' ofropera.- tionswill be described, itY being. understood however thatr successivesimilar' cycles are normally repeated in rapid succession. When. the"mech:- an'isrrr isA disposed-f. as shown in Fig.. 53. al1: of thecomposite slides 24 have been moved away from the. crimping zone I1 asfar as possible, and lowered to cause the fingers 25, 26 thereof to cutthrough the insulation 36 of the wires I6 as#4 in Fig. 1, while, thewires I6 arek resting on the' knife edges 64: of the spreaders 31. Therotors 21 are stationary ati that. time so that no twisting of wires isbeing effected, and the wire. guiding iingers. of the rotors 21 areclamped together by the clamps: 46, althoughv the complementary wires ofeach.. pair will have been temporarily twisted ad@ jacent to their guidewheels 29 during a previous operation ofv these rotors. The dies. I8',I9 are separated to the fullest extent, and while the parts. are in thisposition, the slides 24, 34 of each slide assembly will be movedrelativey to each other so as to separate the fingers 25,v 26 thereofand to produce a bared portion 2U. on each wire: I6, asin Figzz.

Upon completion of this insulation. stripping operation, the spreaders31' will be lowered so as to cause the spread fingers 25, 26 to clearthe tips l2 of these spreaders, whereupon the slides with the wires I6suspended therefrom, will. be moved toward the crimping zone I1, asfdepicted in Fig. 6. TheV dies IS, I9 will remain separated,

but the. pad 22 will have. been withdrawn tolpermit the table 2I. toplace a new card. I4 into position for elevation into the Zone I1 by thelower die I8; and as the slides 24, 34 proceed toward the zone I'I, theypull fresh wire stock from the corresponding supply spools past the wireguide 29 and through the rotors 21. The clamps 46 are also released andthe rotors 2I are revolving, thereby permanently twisting the pairs ofwires IB about each other between each set of transfer fingers 25, 26and the corresponding rotor 2'I but unwinding the temporary twistspreviously applied to wires between each rotor 2'I and its wire guidewheels 29.

This longitudinal transportation of the wires I6 toward the terminalattaching zone Il and the nal twisting of each pair of wires about eachother, continues until the slides 24y 34 have reached the positionillustrated in Fig. 7, whereupon the twisting action of the rotors 21ceases, and the bared portion 29 closely approach final crimpingposition. The pad 22 then moves rearwardly to hold the new cards I4 inproper position while the lowerdies I8 move upwardly and the upper diesI9 move downwardly.

While the twisting rotors 2l are still at rest, the slides 24, 34finally stop in the crimping Zone I 'I and the lower dies I8simultaneously elevate the new card I4 with its terminals I5 directlybeneath the bared wire portions 20, while the upper dies i9 descendthrough the spaces between the ngers 25, 26 of the slides, and cooperatewith each other to rmly clamp the terminals I5 about the adjacentstripped portions 2U of the wires IB, as shown in Fig. 8. During thisfinal crimping operation, the pad 22 will be moved forwardly to clearthe lower die I8 and its card elevating structure, and the slides 24, 34areso formed as not to interfere with the downward crimping motion ofthe upper die I9.

Upon completion of each terminal attaching or crimping operation, theupper dies I9 and the slides 24, 34 coacting therewith, are elevated inunison, but the lower dies I8 remain elevated momentarily while the pad22 is moved beneath the newly attached card I4, and the rotors 2l arerevolved so as to again twist the complementary wires I6 on the oppositesides of each rotor, as depicted in Fig. 9. 'Ihis twisting operationdoes not unwind the previous permanent twists 48 applied to the wires,but in fact starts a new twist 49 in each pair of wires I6 remote fromthe prior twist 48, see Fig. 12.

The wire twisting operation continues while the upper dies I9 are beingwithdrawn from between the transfer lingers 25, 26, and the lower diesI8 are descending, as illustrated in Fig. 10, and during this withdrawalof the lower dies, the pad 22 remains effective to hold the terminalcard I4 which has just been attached to the wires I6, within thecrimping zone ll'. The upward movement of the slides 24, 34 is arrestedwhen the fingers 25, 26 thereof have cleared the wires I and theattached card id, whereupon the slides are ready for their returnstroke.

When the elevated slides 24, 34 and have been moved rearwardly to aposition directly above the spreaders 3l, the twisting operation of therotors 2l ceases, and the spreaders are raised as shown in Figure 11 tocause the points 42 thereof to pass between the adjacent pairs oftwisted Wires i6 and to be clamped against the sides of the points 42,thus assuming the positions shown in Fig. l. The slides 24, 94 aresubsequently lowered and the fingers 25, 2G are simultaneously broughttogether for proper entry between the corresponding sets of spreaders3l, thus placing the apparatus in condition for a repetition of thecycle.

From the foregoing description of the step-bystep operation of themachine, it will be noted that the mechanism is in fact adapted toautomatically and accurately carry on the improved method by removingthe insulation from successive equally spaced portions 28 of the wiresIE and by crimping the terminals of the successive cards I4 directly tothe bare wires I I5 in predetermined order. Because of the fact that theterminals need not necessarily pierce the wires, the improved method andapparatus may be utilized to effect attachment of terminals to eithersolid or stranded wires. The improved insulation removing mechanismfunctions to positively cut and strip the insulation from each area orWire portion 20 without danger of damaging the wires I8, and the finalattachment is effected without resorting to soldering or the like. Whilethe improved method and apparatus are advantageously applicable for theproduction of card and wire chains for telephone systems, this methodand mechanism may also be utilized for other similar purposes, and theimprovement obviously insures production of perfeet electricalconnections between the terminals I5 and wires I9 while the machine isoperating at high speed. While the twisting of complementary pairs ofwires about each other on opposite sides of each point of terminalattachment, is not essential, it is advantageous, and such twisting maybe just as readily effected with the improved method as was possiblewith the method covered by my prior application herein referred to.

It should be understood that it is not desired to limit this inventionto the exact steps of the method or to the precise details ofconstruction of the apparatus, herein shown and described, for variousmodifications within the scope of the appended claims may occur topersons skilled in the art; and it is also contemplated that specicdescriptive terms used herein be given the broadest possibleinterpretation consistent with the disclosure.

I claim:

i. The method of stripping and oi attaching terminals to successivebared portions of a continuous insulation covered wire, which comprises,causing an insulation covered medial portion of the continuous wire torest upon a lower pair of adjoining cutting edges and moving an upperpair of adjoining cutting edges downwardly toward the lower edges in theplane of adjoinment to completely sever the insulation entirely aroundthe wire at said plane, separating the two adjoining sets of cooperatingcutting edges to push the severed ends of the insulation along the wireaway from said plane, dropping the lower cutting edges away from thewire and moving the upper separated cutting edges while still inengagement with the severed separated ends of the insulation in thedirection of extent of the wire to shift the bared wire portion toanother locality and to simultaneously longitudinally advance thecontinuous wire, and clamping a terminal directly about the bared wireportion at said other locality.

2. The method of stripping and of attaching terminals to successivebared portions of a continuous insulation covered wire, which comprises,causing an insulation covered medial portion of the continuous Wire torest upon a lower pair of adjoining cutting edges and moving an upperpair of adjoining cutting edges downwardly toward the lower edges in theplane of adjoinment to completely sever the insulation entirely aroundthe Wire at saidplane, separating the twol adjoining sets of cooperatingcutting edges to push the severed ends of the insulation along the wireaway from the wire, dropping the lower cutting edge away from the wireand moving the upper separated cutting edgesfwhile still in engagement'with the severed separated ends of the insulation in the direction ofextent of the wire to shift the bared wire portion to another localityand to simultaneously longitudinally advance the continuous wire,clamping a terminal directly about the bared Wire portion at said otherlocality, and repeating said stripping and terminal attaching operationsat successive equally spaced localities along the length ofthecontinuous wire.

3.- In a mechanism for stripping and attaching terminals to] successivebared portions of a continuous insulation covered wire, a pair ofadjoining lower cutting edges, means for positioning an insulationcovered medial portion of a continuous wire upon said lower cuttingedges, a pair of adjoiningupper cutting edges movable toward said lowercutting edges in the plane of adjoinment thereof to completely sever theinsulation entirely around the wire at said plane, means for separatingthe said lower and uppen adjoining cutting edges while completelyencirand to simultaneously advance the continuous wire longitudinally,and means for clamping a terminal directlyabout the bared wire portionat said other locality.

4. In a mechanism for stripping and attaching terminals to successivebared portions of a continuous insulation covered wire, a pair ofadjoining lower cutting edges, means for positioning an insulationcovered medial portion of a continuous wire upon said lower cuttingedges, a pair of adjoining upper cutting edges movable toward said lowercutting edges in the plane of adjoinment thereof to completely sever theinsulation entirely around the wire at said plane, means for separatingthe said lower and upper adjoining cutting edges while completelyencircling the wire to push the severed ends of the insulation along theWire away from said plane, means for thereafter removing the lowercutting edges from the wire, means for subsequently moving the upperseparated' cutting edges while still in engagement with the severedseparated insulation ends in the direction of extent of the wire toshift the bared wire portion to another locality and to simultaneouslyadvance the continuous wire longitudinally, means for clamping aterminal directly about the bared wire portion at said other locality,and means for returning said lower and upper cutting edges to insulationsevering and stripping v positions.

KARL H. ANDREN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,800,914 Stull Apr. 14, 19311,835,597 Hill Dec. 8, 1931 1,987,959 Knuuti Jan. 15, 1935 2,142,818Jacobson Jan. 3, 1939 2,217,077 Phillips Oct. 8, 1940 FOREIGN PATENTSNumber Country Date 481,662 Great Britain of 1938

